Unable to set priority for aem workflow item

Hi,

I am trying to save workflow priority by setting priority through workflow process step. However, the property is not getting set to the item even after commiting the change as per the below snippet. In crx/de it still shows the priority as 0(which is 'MEDIUM').  Any suggestions here please.

NOTE : I have give system user all the required permissions (read,write, modify).

Thanks

Raviteja K